The listing was exactly as described, perfectly close to both, Chong Nongsi and Sala Daengt BTS station. Silom Rd is busy, but the Soi Silom 3 where the apartment is located is quiet and therefore a perfect place to stay.
Felix is a great host who was tremendously helpful - he even booked a taxi for us taking the risk we wouldn't pay it and he had to cover the cost (which he did not have to :-)).
I can only recommend this property!